What is a signal?

[valtih1978]

Does

signal A: bit_vector(1 to 5);

define 1 signal, A or 5 elementary signals or 6 signals, one for A and 5
elements?

Is A(3 to 5) also a signal? If so, then, does the declaration define
2^32 signals, for every aggregate we can combine?

What is the target signal in 'A(1) <= value'? Is it an element,
composite or both?

 

[Alan Fitch]

On 26/01/13 16:18, valtih1978 wrote:

Does

signal A: bit_vector(1 to 5);

define 1 signal, A or 5 elementary signals or 6 signals, one for A and 5
elements?

Is A(3 to 5) also a signal? If so, then, does the declaration define
2^32 signals, for every aggregate we can combine?

What is the target signal in 'A(1) <= value'? Is it an element,
composite or both?

See section 4.3 of the 2002 LRM

"There are four classes of objects: constants, signals, variables, and
files. The variable class of objects also has an additional subclass:
shared variables. The class of an explicitly declared object is
specified by the reserved word that must or may appear at the beginning
of the declaration of that object.

For a given object of a composite type, each subelement of that object
is itself an object of the same class and subclass, if any, as the given
object. The value of a composite object is the aggregation of the values
of its subelements."

So an element of signal A in your example is also a signal.

regards
Alan

--
Alan Fitch

 

[rickman]

On 1/26/2013 6:41 PM, Alan Fitch wrote:

On 26/01/13 16:18, valtih1978 wrote:
Does

signal A: bit_vector(1 to 5);

define 1 signal, A or 5 elementary signals or 6 signals, one for A and 5
elements?

Is A(3 to 5) also a signal? If so, then, does the declaration define
2^32 signals, for every aggregate we can combine?

What is the target signal in 'A(1)<= value'? Is it an element,
composite or both?


See section 4.3 of the 2002 LRM

"There are four classes of objects: constants, signals, variables, and
files. The variable class of objects also has an additional subclass:
shared variables. The class of an explicitly declared object is
specified by the reserved word that must or may appear at the beginning
of the declaration of that object.

For a given object of a composite type, each subelement of that object
is itself an object of the same class and subclass, if any, as the given
object. The value of a composite object is the aggregation of the values
of its subelements."

So an element of signal A in your example is also a signal.

He also asked about A(3 to 5) ect, but I don't think that makes 2^32
signals. I think this makes 2^5 - 1 = 31. The null set of coefficients
shouldn't be a signal... A() I mean.

Rick